Nowadays, people at home spend more and more time on the Internet for different purposes, such as checking news and other information, on-line shopping, exchanging information via email or social networking sites, enjoying entertainments such as video or audio clips, etc. A household typically has multiple Internet-accessible devices, such as PCs, smartphones, tablets, game consoles and televisions. Although it is possible to keep track of all the web browsing activities (also known as web events) originated from a particular household, it is difficult to associate a particular web event (e.g., a visit to a particular website during particular time period) with a particular member of the household in a less intrusive manner, which is especially true if the household includes multiple household members that may use different devices to access the Internet at the same time.